A major problem in the operation of pumping systems, such as irrigation pumping systems, wherein the liquid being pumped contains substantial amounts of contaminant particles, is the difficulty in cooling the engine driving the main pump by using the liquid being pumped by the main pump. This problem exists between the contaminant particles in the liquid being pumped clog up the heat exchange passages of the conventional heat exchangers or similar cooling devices in use today. Also, ordinary radiator type engine cooling means use a fan to pass cooling air over the engine's coolant, which arrangement involves a substantial drain of power to drive the fan resulting in substantial energy consumption during operation of the system.
The heat exchanger design in accordance with the present invention for use with water pumping systems provides a solution to the above-discussed problems, and a substitute for and improvement over the conventional radiator type of engine cooling means.
Briefly stated, the heat exchanger design of the present invention comprises an elongated casting having an inlet opening at one end and a discharge opening at the other, the casting including a tubular portion extending between the inlet and discharge openings for defining a first heat exchange chamber internally of the tubular portion. A cover means spaced apart from and enclosing the tubular portion cooperates therewith to define a second heat exchange chamber externally of the tubular portion. There are provided suitable inlet means through which liquid to be cooled may be supplied to the external heat exchange chamber and outlet means through which this liquid may be discharged. In accordance with a novel feature of the invention, the tubular portion is provided with fins cast thereon to extend into both the first and the second heat exchange chambers, there being a plurality of such fins extending generally longitudinally of the tubular portion on both the inside and outside thereof to provide an effective heat exchange action.
There is also provided a novel water pumping system which comprises a water pump having a suction and discharge and arranged to draw water from a supply thereof to the suction and deliver water through the discharge, a water cooled engine arranged to drive the pump, a heat exchanger having a first heat exchange chamber for the cooling medium and a heat exchange chamber for the medium to be cooled. There is also provided conduit means for delivering the water drawn from the water supply to the first heat exchange chamber and from the heat exchanger to the suction of the pump and conduit means for circulating the cooling water of the engine through said second heat exchange chamber.
An advantage of the heat exchanger design in accordance with the invention is that it provides for compactness with no restriction of the main flow and a substantial amount of heat exchange area and thermal flow in a very small space. Moreover, the fins extending into the chamber for the liquid to be cooled extend longitudinally of the tubular portion and cooperate with the cover to provide a plurality of flow conduits providing a minimum of friction loss. The fins extend the effective surface of the tubular portion to give a large heat exchange surface without restricting the longitudinal flow of the liquid through the heat exchanger.
With the water pumping system in accordance with the invention wherein the heat exchanger is located on the suction side of the water pump, it is easy to provide the necessary sealing for the flow because of the low pressures present at this location. Moreover, the design and manufacture of the parts is simplified because there is no problem of withstanding high pressures. Another feature of the pumping system in accordance with the invention is that by eliminating the need for a fan to cool the engine water, all of the horsepower output is put to work pumping water, and there is no consumption of energy for driving a fan or similar cooling device.